Transcutaneous energy transfer (TET) devices are used to transfer energy across a boundary such as skin and other tissue of a patient. For example, a TET device may be used to transfer energy from a source external to a patient's body to a device implanted in the patient's body to power and/or recharge the device. Because the implanted device receives power transcutaneously, the implanted device typically does not require an implanted power source, such as a battery, to operate. As such, the patient is relieved from continual surgical operations to replace and/or recharge the implanted battery or other power sources.